Whale in the River Thames

LONDON, England -- Fears are growing among marine experts after what is believed to be a Northern Bottle-nosed Whale was spotted swimming in the River Thames in the heart of London.

One whale rescuer, Tony Martin, said that such whales were normally only found in very deep water and would require a specialist rescue operation.

"This is a unique experience. Northern Bottle-nosed Whales are normally only found in very deep water so the fact it's here probably means it's ill. This is going to take a number of boats and organization to coax it back into deeper water," Martin told Sky News on Friday.